An electron beam sterilizer is provided with a sterilization chamber formed of lead for preventing an electron beam or an X-ray from leaking, conveying means for conveying an object to be subjected to irradiation or processing (which may be called merely “object” or “irradiation object” hereinlater) disposed in the sterilization chamber, and an electron beam irradiator for irradiating the object in the sterilization chamber with the electron beam.
The electron beam irradiator generates thermal electron by heating a filament in a vacuum in a vacuum chamber, accelerates the electron beam by applying a high voltage to thereby create a high speed electron beam, makes the electron beam generate into the atmosphere through a metallic window foil, such as Ti (Titanium), attached to an irradiation window, and then irradiates the object to be processed with the electron beam, thus performing sterilization and the like processing.
In the electron beam sterilizer, there may be a case in which a spark is generated in the vacuum chamber in which the filaments for generating the electron beam are disposed. When the spark is generated, since the irradiation of the electron beam is not caused till a condition inside the vacuum chamber returns to the condition before the generation of the spark, any sterilizing effect is not expected, and the object may be transferred downstream side without being sterilized. Because of this reason, when the spark is generated, it is necessary to return the condition as soon as possible after stopping the operation of the irradiator. There is provided a control system for an electron beam irradiator capable of possibly shortening a time for restarting the operation of the irradiator (for example, refer to Patent Publication 1.)
The invention of the Patent Publication 1 has a structure such that when the spark is generated inside the vacuum chamber, an output of a power source of the filament is fixed to a value at that time and an output of a high voltage power source of direct current for acceleration voltage is throttled to a value corresponding to the generated spark. When the spark is extinguished, the output value of the high voltage power source of direct current is returned to a value before the generation of the spark, so that the fixing of the output of the power source of the filament is released.    Patent Publication 1: Japanese Patent Publication No. 2848136